1. Field of the Invention
This invention relates to a method of performing a desired operation in one conduit of a system having a pair of conduits and a connecting nipple providing communication between the conduits. More particularly this invention relates to a method of utilizing pump down tools to perform a desired operation in one tubing string of a well at a point axially spaced below from the connecting nipple when the upper locomotive piston of the pump down tool cannot be pumped past the circulating nipple to the work location.
2. The Prior Art
A well is equipped for pump down operations by providing two strings of tubing and a circulating nipple for fluid communication from one string of tubing to the other. Performing an operation, such as setting a tool, in the first string of tubing above the circulating nipple can be accomplished by pumping down a pump down piston locomotive and work tool in the first string of tubing and circulating fluid through the circulating nipple and up the second string of tubing. In this manner, no matter what the bottomhole pressure is, enough force can always be applied through the locomotive piston to the work tool to perform the desired operation. The pump down tools are removed from the well by pumping fluid down the second string of tubing and circulating fluid up through the first string of tubing.
Problems have arisen in the use of pump down equipment when it is desired to perform an operation below the circulating nipple in one of the tubing strings. To provide a means for removing the pump down equipment once the operation is performed the locomotive transport pistons must remain above the circulating nipple so that reverse circulation will be able to lift the equipment out of the tubing string. Extending from the locomotive pistons to the running tool is a stem. The stem may be a sucker rod. The stem is long enough so that the locomotive pistons can remain above the circulating nipple and the running tool can be run down to the desired work location. Sometimes a high differential pressure across the transport pistons is required to apply enough force to the work tool to perform the desired operation. Applying such force downward through the locomotive transport pistons causes the stem to buckle or corkscrew in the tubing. Thus the stem does not efficiently transmit force from the locomotive transport piston to the running tool. With the inefficient transmission of forces from the locomotive piston to the running tool, the operator is uncertain whether or not the desired operation has been properly performed below the circulating nipple.